Horrified outrage at the action of psychopaths has been a common reaction to the Charlie Hebdo massacre. Rightful as it is, however, it is a circular argument: they are mad because they do such things; and they do such things because they are mad. Such is the urge to stay clear of any form of justification, that no explanation is even attempted. There is nothing to explain: it is us against them – a clash of civilizations.

It is a sterile attitude. Explaining is not justifying. A cause is not necessarily a just cause. If we can explain Nazism, Stalinism, wars, crime and violence, we can explain Islamism.

Maajid Nawaz, co-founder and Chairman of the Foundation, has written a great book on his personal experience and on the roots of Islamism. See him here in an excellent debate at the Richmond Forum.

Another enlightening source of information is this work (in French) by Dounia Bouzar and others on the indoctrination of young Islamists. The study, conducted on the analysis of 160 cases, shows that a major component of the process is exposure via Internet to a number of conspiracy theories, all of which have their typical hallmark: they are built on evidence which is portrayed as conclusive. If one is smart enough – savvy, shrewd, sensitive, pure, untainted, knowledgeable – to see the evidence, there is no need to weigh any other evidence: when you have eliminated the impossible…

This is the main route through which people come to believe weird things. It is not madness. And it is not us against them. They are among us. They are in us. Religion can be a catalyst, but it is not the trigger. Take a look at this:

It takes my breath away.

What do you call people who fall into conclusive evidence traps? There is no adequate, inoffensive term. I will call them conclusionists. What motivates them? Distrust of the other side is a key component: evidence matters as long as it is trusted. But it is not necessary. Trustworthy or not, conclusive evidence proves that the other side is wrong.

Another important factor is a craving for certainty – and here is where religion can play a major role. The more uncomfortable we are with uncertainty, the stronger is the urge to look for conclusive evidence, and the higher the risk that we make it up – or that we place our complete trust in people who tell us they have found it.

Of course, it takes more to turn a conclusionist into a murderer. But understanding the roots of his beliefs can be the key to shake him up, before it is too late.